Experiment with strip-tilling leads to strip-cropping

Farmers and resource managers stand by the banks of Rock Creek last Tuesday outside Osage. A watershed group plans to reduce nitrogen in the stream by 41 percent and phosphorous by 29
percent over the next 20 years by implementing practices such as strip till, no till, cover crops and — in one case — not applying fertilizer until the spring.
(Photo:
Charlie Litchfield/The Register
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In 1999, Sponheim was frustrated that every year he had to replant a big chunk of a field that wasn't well tiled. "I was looking for a system where I didn't have to work it in the spring," he said.

Sponheim ended up building the machine he wanted, attaching a strip-till unit to an old planter bar. In the fall, he tilled an 8-inch strip in each row of the field that he could plant into the next year. "I didn't even put fertilizer in the strip," typical "with true strip-tilling," he said.

But he liked how it worked.

The strip is "raised a little bit," Sponheim said. "It dries out and warms up faster in the spring. It's amazing what that does, even in wet muck ground. ... It works really, really well."

A couple of machines later, he and a neighbor started strip-tilling acres for their neighbors. "Most people thought we were nuts," he said. "We just played around with it for a few years. ... We did a lot of modifications."

Now Sponheim uses two machines to strip till 6,000 acres for neighbors, a business that's grown from about 500 acres in the early days.

Sponheim said he and his son, Josh, will spend about 600 hours this fall doing the custom work after they've finished harvesting their own corn and soybeans. They also sell DuPont Pioneer seed and provide variable rate planting and fertilizer prescriptions for their customers.

Variable-rate, or precision farming, allows farmers to use yields, nutrient tests and other data to determine exactly how much seed and fertilizer they need to grow a crop, potentially changing as they move equipment across a field.

Sponheim, who strip-tills both corn and soybean acres, has become a believer in the conservation practice that leaves most of the crop residue on the field to help build organic matter. It also reduces erosion and keeps fertilizer from moving from the soil.

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Adam Kiel, an Iowa Soybean water resources manager, wades through Rock Creek on Tuesday, Sept. 16, 2014, outside Osage, Iowa. The watershed group plans to reduce nitrogen in the stream by 41 percent and phosphorous by 29 percent over an estimated 20 years. Charlie Litchfield/The Register

Adam Kiel, an Iowa Soybean water resources manager, sifts through the waters of Rock Creek on Tuesday, Sept. 16, 2014, outside Osage, Iowa. The watershed group plans to reduce nitrogen in the stream by 41 percent and phosphorous by 29 percent over an estimated 20 years. Charlie Litchfield/The Register

A group of farmers and resource managers stand by the banks of the Rock Creek on Tuesday, Sept. 16, 2014, outside Osage, Iowa. The watershed group plans to reduce nitrogen in the stream by 41 percent and phosphorous by 29 percent over the next 20 years by implementing practices such as strip till, no till, cover crops and in one case, not applying fertilizer until the spring, to better prevent nitrogen and phosphorous losses Charlie Litchfield/The Register

Farmer Dana Norby walks out of a farm field on Tuesday, Sept. 16, 2014, outside Osage, Iowa. Norby is one of several farmers in the area who are part of an initiative to improve the water quality in Rock Creek, a watershed with 44,787 acres that drain to the point where Rock Creek meets the Cedar River, southwest of Osage Charlie Litchfield/The Register

Farmers Dana Norby, left, and Wayne Fredericks, right, stand with Adam Kiel, an Iowa Soybean water resources manager, near a farm field on Tuesday, Sept. 16, 2014, outside Osage, Iowa. The group is part of an initiative to improve the water quality in Rock Creek, a watershed with 44,787 acres that drain to the point where Rock Creek meets the Cedar River, southwest of Osage. Charlie Litchfield/The Register

Farmers Wayne Fredericks, from left, and Dean Sponheim stand and talk near a farm field on Tuesday, Sept. 16, 2014, outside Osage, Iowa. The group is part of an initiative to improve the water quality in Rock Creek, a watershed with 44,787 acres that drain to the point where Rock Creek meets the Cedar River, southwest of Osage. Charlie Litchfield/The Register

Adam Kiel, an Iowa Soybean water resources manager, wades through Rock Creek on Tuesday, Sept. 16, 2014, outside Osage, Iowa. The watershed group plans to reduce nitrogen in the stream by 41 percent and phosphorous by 29 percent over an estimated 20 years. Charlie Litchfield/The Register

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Sponheim's experimentation with strip-tilling has led to other conservation practices, including strip-cropping — eight rows each of alternating corn and soybeans.

He believes strip-cropping, an old practice that's gaining new popularity, allows for better use of nutrients, and it gives nature an opportunity to build better yields. Sponheim said the soybeans allow more sunlight and air to flow through the field.

"If you have an 80-acre field of corn, it becomes a sauna in there," he said. "There's hardly any air moving in the corn when it's tasseling ... but if we open it up with bean strips, now all of a sudden we've reduced the temperature of that cornfield tremendously."

Sponheim said the yields on the outside corn rows are up to 35 percent higher than the inside rows. And the soybean yields are the same, or slightly better, than with "block cropping."

Sponheim also is testing strip-cropping four rows of alternating corn and soybeans. "It makes every row an outside row."

And strip cropping better enables cover crops such as cereal rye to grow. Many farmers have the cover crop seeds flown over corn and soybean fields before they're harvested.

Sponheim, who's testing different cover crop varieties and application methods, sees the over-winter crop as an "insurance policy," allowing him to tap the nitrogen and phosphorous that the corn and soybean crops may not have used.

Cover crops use the nutrients as they grow, releasing them for corn and soybeans the next year as they decay.

Sponheim has come a long way from 15 years ago, when he first started strip-tilling. Back then, he moldboard plowed "fence to fence."

"If there was a single corn stalk standing up, you did an awful job of plowing," he said, cringing now, thinking about the erosion it caused. "I remember springs when we had black water running down the ditches. It was terrible."

Sponheim believes strip-tilling, precision farming and other changes better position his farm, and those of his neighbors, for extreme weather conditions.

Keeping more stalks, husks and other crop residue on the land is improving the soil health, enabling it to better hold moisture needed during droughts, and keep nutrients from leaving fields during heavy rains, he said.

"I have two grandsons ... and we want to leave something for them," Sponheim said.